Method and apparatus for transversely slitting sheet material



METHOD AND APPARATUS FOR TRANSVERSELY SLITTING SHEET MATERIAL Filed April 18, 1960 Jan. 1, 1963 F. D. KARKOSKA lml 3 Sheets-Sheet 1 Jiaezz/ar:

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Jan. 1, 1963 F. n. KARKOSKA 3,071,175

METHOD AND APPARATUS FOR TRANSVERSELY SLITTING SHEET MATERIAL Filed April 18, 1960 3 Sheets-Sheet 2 Jan. 1, 1963 F. D.- KARKOSKA 3,071,175

METHOD AND APPARATUS FOR TRANSVERSELY SLITTING SHEET MATERIAL Filfid April 18, 1960 3 Sheets-Sheet 3 United States Patent Ofiice 3,071,175 Patented Jan. 1, 1963 3,071,175 METHOD AND APPARATUS FOR TRANSVERSELY dLllTllNG SHEET MATERIAL Frank I). Karhoslra, Oalr Lawn, Ill.

(5211 S. Haisted St., Chicago, Ell.) Filed Apr. 18, 196i), Ser. No. 23,048

23 Claims. (Cl. 153--2) This invention relates to a method and apparatus for transversely shearing an elongated strip of a sheet material. It is more specifically concerned with a method and apparatus for transversely slitting sheet material to produce narrow bands which are helically formed about the longitudinal axis of the bands.

In fabricating material for decorative displays, it is important that the final product be fashioned from materials which have attention-attracting qualities. Vivid colors, either fluorescent or plain, rotating spinners, festoons of gaily colored flags, banners, or pennants are conventional expedients which are utilized as means for attracting attention or providing a decorative effect for various display techniques. Quite frequently, garlands, festoons, and other streamer-like strip material are sus ended or strung between spaced supports in order to provide a decoration scheme for use in either outdoor or indoor installations. The streamers are generally made from ribbons or strips of crepe paper or the like which are given a helical twist in order to enhance the decorative appeal of the strip. Various other materials, such as plastic or foil-like sheet metal, have also been employed in elongated strips which have been helically twisted for their entire length and used as streamers for decoration purposes.

According to this invention, it has been found that the attractiveness of streamer-type decorations can be enhanced by employing a foil-like metal which has been transversely slit to provide a plurality of narrow bands attached to a common ribbon running the length of the streamer. When the streamer of this nature is employed and twisted into a helical form, the various bands extend radially in the form of bristle-like members to provide an attractive display device. The allurement of the streamer-type of decoration is also improved by helically forming the individual bands, such that a helix is formed along the longitudinal axis of each individual band.

In addition to being employed as streamer material slit strip with the helically formed bands can be advantageously employed in the fabrication of artificial Christmas trees, wherein the streamer material is helically wound on a rod or other slender support means to simulate a tree branch. A plurality of artificial branches so fabricated are then inserted in a plurality of holes provided in a suitable upright standard to the conical form of natural Christmas trees. Artificial trees prefabricated in this manner are illustrated by Hankus Patent 2,889,650.

Referring to the drawings:

FIGURE 1 is a plan view of a specific embodiment of a slitter apparatus of this invention showing the sheet material strip supply reel, the various strip guides and the slitting mechanism;

FIGURE 2 is a side elevation view of the slitting apparatus shown in FIGURE 1 illustrating the strip of sheet material fed from a roll, shown in fragmentary form, being guided to the feed mechanism and thereafter fed into the cutter end of the slitting mechanism;

FIGURE 3 is an end view of the slitter apparatus shown in FIGURE 1 looking at the slitter apparatus from the slitter mechanism end;

FIGURE 4 is an enlarged fragmentary view of the strip feed and slitting mechanism showing the shearing elements employed in the illustrative specific embodiment of this invention;

' of the channel members.

FIGURE 5 is a transverse cross-sectional view of the strip hold down element and stationary shear plate assembly taken along line 5-5 of FlGURE 4;

FIGURE 6 is an enlarged cross-sectional view taken through line 66 of FIGURE 1 illustrating the bearing block arrangement employed for the sheet material feed and the shear blade rotor;

FIGURE 7 is a cross-sectional view of the rotor mechanism taken along line '77 of FIGURE 1 showing the helical form of the shear blade;

FIGURES 8, 9 and 10- illustrate schematically the pro gressive preforming and shearing operation effected by the apparatus of this invention by the cooperation of the shear plate and the shear blade mounted on the rotating rotor; and

FIGURE 11 illustrates an alternative position for shear plate in relation to the shear blade.

Referring to the drawings it will be seen that the illustrative specific embodiment presented therein comprises a frame it) prepared from channel members ill and 12 held in spaced relation by spacer 13 as well as various other elements of the apparatus mounted on the upper flanges or between the opposed webs of the channel mem bers 11 and 12. As shown, the various elements of the apparatus are held in position by threaded fasteners which secure the elements to the frame 10. It is apparent, however, that other fastening means such as welding or the like can be employed. In addition various components of the apparatus can be integrally cast into a unitary frame and the build-up construction shown avoided.

A sheet metal supply is provided by means of brackets 14 and 15 which are mounted in an upright position on the upper flanges of channel members 11 and 12. The brackets in the form of truncated triangular members, as shown, are provided with semi-circular recesses in the truncated portion of the brackets which are adapted to receive the flanged supports 16 and 17 between which feed supply reel supporting arbor 18 is mounted. The feed supply assembly is held in place by threaded rod 19 and integrated by means of threaded fastener 29. The inner ends of flanged supports are fitted in the opposed open ends of the tubular arbor 18 which is used to support the roll of sheet material as it is fed through the machine. Flanged guide collars 22 and 23 are slidably mounted on arbor 2i and are adapted to be locked in position by means of set screws 24 and 25 which engage the outer surface of arbor 18 and rotatably hold the roll of sheet material 26 firmly on the supply arbor.

A pair of guide bars 30 and 31 are employed to guide the strip of sheet material 26 through the feed mechanism as it is fed through the shearing elements of the slitter apparatus of this invention. Guide bar 30 is mounted between the opposed web members of channel members 11 and 12 substantially intermediate the flanged elements Guide 31 on the other hand is mounted in an elevated position, with respect to guide bar 30, on the upper flange of the channel members 11 and 12. These guides are fabricated from substantially the same elements which are employed to construct the sheet material supply arbor assembly hereinbefore discussed. AXles 32 and 33 suitably journaled on the frame are used to hold flanged supports 34 and 35, 36 and 37. Tubular sleeves 38 and 39 are mounted on the flanged supports and held in place thereon. Pairs of guide collars 40 and 41, 42 and 43 are respectively positioned on tubular guide bars 38 and 39 to align the sheet material as it passes over the guides. Although the guide bar 38 and 39 as shown are stationary, rotatable guide bars can be used if desired.

A feed mechanism 45 comprising a pair of cooperating rotating rolls 46 and 47 are used to feed sheet material continuously from the roll into the slitting elements which will hereinafter be discussed. The roll elements 46 and 47 of the feed mechanism 45 are respectively journaled in bearing blocks 48 and 49, 50 and 51. The lower hearing elements 49 and 51 are mounted on the upper flange of the channel members by suitable threaded fasteners 54 and 55 which traverse the bearing block and the flange element of the channel member. As shown in FIGURE 6, the upper bearing block is joined to the lower block of the bearing pair by means of a hinge 52 and 53 and the two bearing blocks coupled to one another by a coil spring 55 which is secured to the adjacent faces of bearing blocks 48 and 49 by means of eye bolts 56 and 57 which are threadably secured to the face of the respective hearing blocks 48 and 49. As shown, feed roller 46 has a larger diameter than feed roll 47. In addition feed roll 47 is surfaced with a rubber face whereas feed roller 46 is a steel surface roll. Both of the feed rollers 46 and 47 are mounted on axles 59 and 66 which are journaled in bearing block pairs 48 and 49, Stl and 51. Roll 47 is driven as will hereinafter be discussed.

The slitting mechanism of the apparatus of this invention comprise a stationary shear plate 65 which is held in place on an upper shear plate support bar 66 by means of threaded fasteners 67. A lower shear plate support 68 is mounted on the frame It by means of angle brackets 69 and 70 which are mounted on the opposed faces of the web elements of channel members 11 and 12. Spacers 71 and 72 are employed to permit the height and position of shear plate 65 to be adjusted relative to the rotor element of the rotating shear blades. To permit lateral as well as vertical adjustment, slots 73 and 74' are provided in the face of upper shear plate support bar 66. A hold down plate 64 is also mounted on shear plate support bar 66 in spaced relationship to the upper face of shear plate 65 to provide a spacing through which can be fed the sheet material 26 which is to be sheared in the slitting mechanism of this invention.

A flying shear blade 75 is mounted on the face rotatable rotor 76 which is journaled between bearing blocks 77 and 78 by means of axle 79. The opposed ends of axle 79 extend beyond the outer faces of bearing blocks 77 and 78 to provide extensions whereon drive means can be mounted for effecting the interaction of the feed rolls and slitter mechanism. On one terminal end of axle 79 a V-grooved pulley 80 is mounted. Any suitable drive means can be used to drive pulley 80 by means of a V- belt or the like. The other end of axle 79 is fitted a pinion gear which is the driving gear 81 employed to drive the the amount of sheet material which is fed in relation to the cutting action of shear blade 75 which is mounted on rotatable rotor 76. The gear ratio which is selected is determined by the width of the transverse bands which are cut and is used to control this characteristic of the slit strip material. In one embodiment wherein A" wide bands were slit employing a As" diameter steel rod, the rotation was about 19 times faster than the speed of rotation of the feed roll.

After the strip material passes between the shearing portion of shear blade 75 and shear plate 75 it moves to an obliquely mounted take-off plate 90 from which it is removed and delivered to a suitable storage facility. For

example, the strip material can be taken off and wrapped about a core of cardboard or other strip material and held in place thereon.

The gear housing enclosure 83 is fastened to the channel member 12 by means of brackets 91 and 92 to which is'fastened an inner face plate 93 which serves as a backing for the gear housing enclosure in order to provide a fluid-tight enclosure.

In the illustrative embodiment shown in the drawings the shear blade is a drill steel rod having a circular cross-section and being helically mounted on the face of the rotatable rotor 76. As shown the extent of the helix formed by the cutter blade 75 is a 180 helix. The blade 75 is held in place by collars 94 and 95. Holes are provided in the opposed faces of the collars into which the ends of the blade are inserted. The selected position of the collars 94 and 5 is maintained by a conventional set screw arrangement. By employing a round cutter blade such as shown, there is provided a preforming portion of the blade as well as a shearing portion which is utilized as hereinafter will be discussed. In addition to a round cross-section shearing blade a variety of other crosssectional configurations can be employed depending upon the results desired by the slitting machine of this invention. the event that the desired helical form is to be imparted to the transverse bands of sheet material, it is essential that the cutting blade be provide-d with a preforming portion and a shearing portion. Accordingly, diamondshaped or rectangular cutting blades can be used provided they are mounted on the face of the rotatable rotor with the diagonal portion of the cross-section radially aligned with the rotatable rotor. Other configura tions which simply provide a cutting edge can be employed, however, they will not effect the desirable helical forming of the transverse bands which are slit from the sheet material. To avoid obliquely shearing the slit bands the axis of the rotatable rotor 76 is adjusted with respect to the longitudinal axis of the frame 10. Generally the axis is offset a distance about equal to the width of the slit band.

The operation of the slitter apparatus of this invention is schematically illustrated in FIGURES 8, 9 and 10 which show the progressive preforming and shearing operation which instantaneously follows. The sheet material 26 is fed from the roll supply and passed over guide bars 36 and 31 between the drive rollers 46 and 47 of the drive mechanism. The free end of the sheet material is passed underneath hold-down plate 64 and the machine is operated by actuating a prime mover which effects the rotation of drive pulley 86. With the correlated rotation of rotatable rotor 76 and drive mechanism 45, the sheet material is fed across the shearing edge of shear plate 65. The shear plate 65 is adjusted so that the cutting blade 75 engages the shearing edge of cutter plate 65 as it progressively moves in shearing relationship thereacross during the rotation of rotor 76. As shown, the height of shear plate 75 is adjusted so that the shearing edge of cutter blade 75 is in shearing contact with shearing edge the of shear plate 65 when the radial alignment of rotor 76 and shearing blade 75 is parallel to the shearing face of shear plate 65 and the point of tangency on shear blade 75 in contact with shearing edge of shear plate 65 is normal to the radial alignment of rotor 76 and the shearing surface of shear plate 65.

Referring to FIGURES 8, 9 and 10 there will be seen the progressive initial preforming and subsequent shearing operation effected by the relationship of shear plate and shear blade shown in the illustrative drawings. In FIGURE 9 the angular position of shear blade 75 with respect to the shearing edge of shear plate 65 is such that the leading edge of the sheet material to be cut has progressed a small amount beyond the leading edge without being contacted by the shear blade 75. Thereafter the preforming portion of the shear blade '75 contacts the portion of the sheet material which is extending beyond the shearing edge of shear plate 65, and urges the sheet material downwardly over the shearing edge without affecting its slitting. Because of the natural resiliency of the material it has a tendency to assume a curved form conforming with the configuration of the cutter blade. Thereafter, the shearing edge of the shearing blade 75 moves into cutting relationship with the shearing edge th of shear plate 65 to effect the severance of the sheet material at that point. As it will be noted the cutting blade '75 is helically mounted on the face of rotatable rotor 76 so that there is progressively effected a pointby-point preforming and shearing of the sheet material as the cutter blade progresses across the face or cutting edge of the cutter plate 65. It is the preforming operation which is effected on the leading edge of the band followed by the slitting of the band at its trailing edge' which provides the helical formation of the band in the most desired form.

In the event that it is necessary to retain the slit bands in an integrated continuous strip, a side ribbon coextensive with the marginal edge of the strip material is allowed to remain. This band is provided by employing a shear plate which is not as long as the strip material is wide, thereby leaving an edge portion on the sheet material which is not cut by the continued rotation of the cutting blade 75. In the event that the retaining ribbon is to be positioned on the opposite side or between the marginal edges of the strip, the shape of the shear plate can be effected accordingly in order to produce the desired results. As shown in the illustrative embodiment the sheet material which is fed through the slitter will have a convinuons ribbon running along the edge of the strip material adjacent that side of the slitter on which the speed reduction gearing is employed.

As previously pointed out the shear plate 65 is adjustable in order to provide a variety of configurations on the slit bands produced by this invention by moving the shear plate downwardly and laterally inward. By removing spacers 7 1 and 72, or replacing them with other spacers of varying thicknesses, the extent of helical twist and the slit band can be provided in the position as shown. A minimum twisting is provided by repositioning the shear plate downwardly and inwardly. The amount of twist can be varied to the point no twist is produced and a fiat band results from the shearing operation. The position of the shear plate 65 in relation to cutter blade '75 to effect this result is shown in FIGURE 11. With the shear plate in this position, substantially flat, untwisted bands are produced.

In selecting the sheet material which is employed in the instant invention, a variety of materials can be utilized depending upon the desired end result. If it is desirable to produce a strip material wherein each of the transverse bands is permanently twisted helically about its longitudinal axis, a ductile material such as a metal foil formed from aluminum or the like, selected plastics, and other materials are employed. it is necessary that the type of material which is employed for this type of fabrication be such that a permanent set can be produced in the sheet material during the preforming and shearing operation. Otherwise, if the material has a natural resiliency, the helix which is formed during the slitting operation will spring back to the original flat shape of the sheet material. In the event that a simple slitting operation is effected, thin sheets of metal, paper, cloth, or other fabrics can be utilized.

The apparatus shown in the drawings, which in FIG- URES 1-7 is reproduced in one-half scale, was employed in the production of strip material for use in the fabrication of artificial metal Christmas trees. The sheet material used was aluminum metal foil 0.003" thick and 3%" wide. The rotor was rotated at 1750 rpm. and a 19 to 1 gear ratio selected to rotate the rubber faced feed roller at about 90 r.p.m. By employing a 6" diameter drill steel rod helically mounted on the face of the rotor through an angle of 180 over the length of the rotor and the above feed rate, /s wide bands were cut. Each band was helically twisted about its longitudinal axis about 270. The length of the shear plate was correlated to the longitudinal length of the shear blade to permit a A wide marginal ribbon coextensive with the length of the sheared strip. The ribbon connected the slit bands C8 in side-by-side relationship to produce an integral arrangement of ribbon and bands.

Although the subject invention is described with reference to the illustrative embodiment it is evident that variations and modifications of the subject invention can be made by those skilled in the art without departing from the scope of this invention. Conventional materials of construction can be employed and alternative designs used for arranging the elements in their sequential pattern.

What is claimed is:

1. A slitter for slitting sheet material transversely to the direction of material feed which comprises a stationary shear plate provided with a shearing edge, feed means for continuously feeding strip sheet material across the top of said shear plate, a shear means comprising a rotatable rotor and a shearing blade mounted on the outer surface of said rotor, said shearing blade cooperating with said shear plate to shear said material, said shearing occurring progressively along said shearing edge during each slitting step, means for driving said rotor, and means for driving said feed means at a speed synchronized with the speed of said rotor.

2. A slitter for slitting sheet material transversely to the direction of material feed which comprises a stationary shear plate provided with a shearing edge, feed means for continuously feeding strip sheet material across the top of said shear plate, a shear means comprising a rotatable rotor and a shearing blade mounted on the outer surface of said rotor, said shearing blade cooperating with said shear plate to initially preform the leading edge of said sheet material and thereafter shear said material, said preforming and shearing occurring progressively along said shearing edge during each slitting step, a holddown plate overlaying said shear plate and substantially coextensive therewith, means for driving said rotor, means for driving said feed means at a speed synchronized with the speed of said rotor whereby the leading edge of a portion of the sheet material is preformed and the trailing edge of the portion of the sheet material is sheared.

3. A slitter for slitting sheet material transversely to the direction of material feed which comprises a stationary shear plate provided with a shearing edge, feed means for continuously feeding strip sheet material across the top of said shear plate, a shear means comprising a rotatable rotor and a shearing blade mounted on the outer surface of said rotor, said shearing blade having a preforming portion and shearing portion cooperating with said shear plate to initially preform the leading edge of said sheet material and thereafter shear said material, said preforming and shearing occurring progressively along said shearing edge during each slitting step, a holddown plate overlaying said shear plate and substantially coextensive therewith, means for driving said rotor, means for driving said feed means at a speed synchronized with the speed of said rotor whereby the leading edge of a portion of the sheet material is preformed and the trailing edge of the portion of the sheet material is sheared.

4. A slitter for slitting sheet material transversely to the direction of material feed Which comprises a stationary shear plate provided with a shearing edge, feed means for continuously feeding strip sheet material across the top of said shear plate, a shear means comprising a rotatable rotor and a helically mounted shearing blade mounted on the outer surface of said rotor, said shearing blade having a preforming portion and shearing portion cooperating with said shear plate to initially preform the leading edge of said sheet material and thereafter shear said material, said preforming and shearing occurring progressively along said shearing edge during each slitting step, a hold-down plate overlaying said shear plate and substantially coextensive therewith, means for driving said rotor, means for driving said feed means at a speed synchronized with the speed of said rotor whereby the the leading edge of a portion of the sheet material is preformed and the trailing edge of the portion of the sheet material is sheared.

5. A slitter for slitting sheet material transversely to the direction of material feed which comprises a stationary shear plate provided with a shearing edge, feed means for continuously feeding strip sheet material across the top of said shear plate, a shear means comprising a rotatable rotor and a helically mounted shearing blade mounted on the outer surface of said rotor, said shearing blade being circular in cross-section and having a preforrning portion and shearing portion cooperating with said shear plate to initially preform the leading edge of said sheet material and thereafter shear said material, said preforming and shearing occurring progressively along said shearing edge during each slitting step, a hold down plate overlaying said shear plate and substantially coextensive therewith, means for driving said rotor, means for driving said feed means at a speed synchronized with the speed of said rotor whereby the leading edge of a portion of the sheet material is preformed and the trailing edge of the portion of the sheet material is sheared.

6. A slitter for slitting sheet material transversely to the direction of material feed to produce a plurality of lateral bands which comprises a stationary shear plate provided with a shearing edge, said shear plate being reciprocatively and laterally adjustable, feed means for continuously feeding strip sheet material across the top of said shear plate, a shear means comprising a rotatable rotor and a shearing blade mounted on the outer surface of said rotor, said shearing blade having a preforming portion and shearing portion cooperating with said shear plate to initially preform the leading edge of said sheet material and thereafter shear said material, said preforming and shearing occurring progressively along said shearing edge during each slitting step, a hold-down plate overlaying said shear plate and substantially coextensive therewith, means for driving said rotor, a speed reduction gear train connecting said rotor and said feed means to drive said feed means at a speed synchronized with the speed of said rotor whereby the leading edge of the portion of the sheet material is preformed and the trailing edge of the slit portion of the sheet material is sheared, the gear ratio of said gear train being selected to advance said material the width of said bands during the slitting action.

7. A slitter for slitting sheet material transversely to the direction of material feed to produce a plurality of lateral bands which comprises a stationary shear plate provided with a shearing edge, said shear plate being reciprocatively and laterally adjustable, feed means for continuously feeding strip sheet material across said shear plate, a shear means comprising a rotatable rotor having a solid hub and a helically mounted shearing blade mounted on the outer surface of said rotor hub, said shearing blade being circular in cross-section and having a preforming portion and shearing portion cooperating with said shear plate to initially preform the leading edge of said sheet material and thereafter shear said material, said preforrning and shearing occurring progressively along said shearing edge during each slitting step, a hold-down plate overlaying said shear plate and substantially coextensive therewith, means for driving said rotor, a speed reduction gear train connecting said rotor and said feed means to drive said feed means at a speed synchronized with the speed of said rotor whereby the leading edge of the portion of the sheet material is preformed and the trailing edge of the slit portion of the sheet material is sheared, the gear ratio of said gear train be ng selected to advance said material the width of said bands during the slitting action.

8. A slitter in accordance with claim 7 in which said shear plate is shorter than the longitudinal length of said shearing blade.

9. A method for producing a helical band of a deformable sheet material twisted about its longitudinal axis which comprises continuously feeding a strip of a sheet material in a longitudinal direction across the shearing edge of a stationary shear plate, progresively transversely preforming the portion of the strip forming the leading edge of said band against said shearing edge to produce a flange which extends in a lateral downward direction and instantaneously thereafter progressively transversely shearing the portion of said strip forming the trailing edge of said band on said shearing edge.

10. A method in accordance with claim 9 in which said sheet material is a foil-like ductile metal.

11. A method in accordance with claim 10 in which said sheet material is aluminum foil.

12. In a method for producing a continuous strip of a sheet material comprising a plurality of permanently formed helical transverse bands maintained integral with said strip by a continuous longitudinal ribbon of said material common to said bands, said bands being twisted about their longitudinal axis, the steps of continuously feeding a strip of ductile, metallic sheet material in a longitudinal direction across the shearing edge of a stationary shear plate, progressively transversely preforming the portion of the strip forming the leading edge of said band against said shearing edge to produce a flange which extends in a lateral downward direction and instantaneously thereafter progressively transversely shearing the portion of said strip forming the trailing edge of said band on said shearing edge, said shearing extending less than the Width of said strip.

13. In a method for producing a continuous strip of a sheet material comprising a plurality of permanently formed helical transverse bands maintained integral with said strip by a continuous longitudinal ribbon of said material common to said bands along a marginal edge of said strip, said bands being twisted about their longitudinal axis, the steps of continuously feeding a strip of ductile, metallic sheet material in a longitudinal direction across the shearing edge of a stationary shear plate, progresively transversely preforming the portion of the strip forming the leading edge of said hand against said shearing edge to produce a flange which extends in a lateral downward direction and instantaneously thereafter progressively transversely shearing the portion of said strip forming the trailing edge of said band on said shearing edge, said shearing extending less than the Width of said strip to adjacent a marginal edge of said strip.

14. A method in accordance with claim 13 in which said sheet material is a foil-like ductile metal.

15. -A method in accordance with claim 14- in which said sheet material is aluminum foil.

16. A strip of a sheet material comprising a plurality of permanently formed helical transverse bands maintained integral with said strip by a continuous longitudinal ribbon of said material common to said bands, said bands being twisted about their longitudinal axis, in excess of about said strip being formed by continuously feeding a strip of ductile, metallic sheet material across the shearing edge of a stationary shear plate, progressively transversely preforming the portion of the strip forming the leading edge of said hand against said shearing edge to produce a lateral downwardly directed flange and instantaneously thereafter progressively transversely shear ing the portion of said strip forming the trailing edge of said band on said shearing edge, said shearing extending less than the Width of said strip.

17. A strip in accordance with claim 16 in which said sheet material is a foil-like ductile metal.

18. A strip in accordance with claim 17 in which said sheet material is aluminum foil.

19. A slitter for slitting sheet material transversely to the direction of material feed comprising a stationary shear plate across the top of which the material is fed, said shear plate including a shearing edge, a rotatable rotor, and a helically mounted shearing blade mounted on the outer surface of said rotatable rotor.

20. The slitter in accordance with claim 19 in which said shear plate is shorter than the longitudinal length of said shearing blade.

21. The slitter in accord .nce with claim 19, said rotatable rotor having an axle lying generally within the 10 23. The slitter in accordance with claim 19 including means for driving said feed means at a speed synchronized with the speed of said rotor whereby the leading edge of the band of the sheet material is preformed and the trailplane formed by the top of said shear plate, said shearing 5 ing edge of the band of the sheet material is sheared.

blade having a preforming portion and a shearing portion cooperating with said shear plate to initially preform the leading edge of the band of said sheet material and thereafter shear the trailing edge of the band of said material.

22. The slitter in accordance with claim 19 wherein said shear plate is reciprocatively and laterally adjustable for varying the helical twist of the bands of the sheet material.

References Cited in the tile of this patent UNITED STATES PATENTS 735,936 Blakey et al Aug. 11, 1903 1,577,619 Gammeter Mar. 23, 1926 2,016,735 Abramson et a1. Oct. 8, 1935 2,754,906 Gundlach July 17, 1956 

1. A SLITTER FOR SLITTING SHEET MATERIAL TRANSVERSELY TO THE DIRECTION OF MATERIAL FEED WHICH COMPRISES A STATIONARY SHEAR PLATE PROVIDED WITH A SHEARING EDGE, FEED MEANS FOR CONTINUOUSLY FEEDING STRIP SHEET MATERIAL ACROSS THE TOP OF SAID SHEAR PLATE, A SHEAR MEANS COMPRISING A ROTATABLE ROTOR AND A SHEARING BLADE MOUNTED ON THE OUTER SURFACE OF SAID ROTOR, SAID SHEARING BLADE COOPERATING 